Fuzzy control process for switching power supplies, and device for performing it

A process for the fuzzy control of switching power supplies which have at least one inductor and at least one switching device, and a device for performing this control, the particularity whereof resides in the fact that it comprises the following steps: measuring the value of the current on the inductor; measuring the value of the input voltage of the switching power supply; measuring an error generated between a reference voltage and an output voltage of the power supply; defining fuzzy membership functions for the value of the current on the inductor, for the input voltage value, and for the error; defining an output membership function for the value of the duty cycle of the power supply; defining multiple fuzzy inference rules to which the measured values and the membership functions are applied calculating the corresponding weight functions of the membership functions; defuzzifying the results obtained by means of the weight function calculation and the application of fuzzy rules so as to obtain a real value of the duty cycle which is suitable to drive the switching device.

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Claims

1. A process for the fuzzy control of a switching power supply which has at least one inductor and at least one switching device, comprising the following steps:

measuring a value of a current in said inductor;
measuring a value of an input voltage of said switching power supply;
measuring an error generated between a reference voltage and an output voltage of said power supply;
defining fuzzy membership functions for said value of the current in said inductor, for said input voltage value and for said error;
defining an output membership function for a value of a duty cycle of said power supply;
defining multiple fuzzy inference rules to which said measured values and said membership functions are applied;
calculating corresponding weight functions of said membership functions; and
defuzzifying results obtained by means of said weight function calculation and said application of fuzzy rules to obtain a real value of said duty cycle, which real value is for driving said switching device.

2. A process according to claim 1, wherein said process employs as said switching device a power transistor.

3. A process according to claim 2, further comprising the following steps:

measuring a value of a temperature of said power transistor; and
defining a membership function for said temperature value.

4. A process according to claim 3, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

5. A process according to claim 4, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

6. A process according to claim 5, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

7. A process according to claim 6, wherein said calculation of said weight functions occurs on said antecedents.

8. A process according to claim 5, wherein said calculation of said weight functions occurs on said antecedents.

9. A process according to claim 4, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

10. A process according to claim 9, wherein said calculation of said weight functions occurs on antecedents.

11. A process according to claim 4, wherein said calculation of said weight functions occurs on antecedents.

12. A process according to claim 3, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

13. A process according to claim 12, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

14. A process according to claim 13, wherein said calculation of said weight functions occurs on said antecedents.

15. A process according to claim 12, wherein said calculation of said weight functions occurs on said antecedents.

16. A process according to claim 3, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

17. A process according to claim 16, wherein said calculation of said weight functions occurs on antecedents.

18. A process according to claim 3, wherein said calculation of said weight functions occurs on antecedents.

19. A process according to claim 2, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

20. A process according to claim 19, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

21. A process according to claim 20, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

22. A process according to claim 21, wherein said calculation of said weight functions occurs on said antecedents.

23. A process according to claim 20, wherein said calculation of said weight functions occurs on said antecedents.

24. A process according to claim 19, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

25. A process according to claim 24, wherein said calculation of said weight functions occurs on antecedents.

26. A process according to claim 19, wherein said calculation of said weight functions occurs on antecedents.

27. A process according to claim 2, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

28. A process according to claim 27, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

29. A process according to claim 28, wherein said calculation of said weight functions occurs on said antecedents.

30. A process according to claim 27, wherein said calculation of said weight functions occurs on said antecedents.

31. A process according to claim 2, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

32. A process according to claim 31, wherein said calculation of said weight functions occurs on antecedents.

33. A process according to claim 2, wherein said calculation of said weight functions occurs on antecedents.

34. A process according to claim 1, further comprising the following steps:

measuring a value of a temperature of said power transistor; and
defining a membership function for said temperature value.

35. A process according to claim 34, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

36. A process according to claim 35, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

37. A process according to claim 36, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

38. A process according to claim 37, wherein said calculation of said weight functions occurs on said antecedents.

39. A process according to claim 36, wherein said calculation of said weight functions occurs on said antecedents.

40. A process according to claim 35, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

41. A process according to claim 40, wherein said calculation of said weight functions occurs on antecedents.

42. A process according to claim 35, wherein said calculation of said weight functions occurs on antecedents.

43. A process according to claim 34, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

44. A process according to claim 43, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

45. A process according to claim 44, wherein said calculation of said weight functions occurs on said antecedents.

46. A process according to claim 43, wherein said calculation of said weight functions occurs on said antecedents.

47. A process according to claim 34, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

48. A process according to claim 47, wherein said calculation of said weight functions occurs on antecedents.

49. A process according to claim 34, wherein said calculation of said weight functions occurs on antecedents.

50. A process according to claim 1, further comprising the step of defining a membership function for the value of at least one of a base current and a gate voltage of said switching device; and wherein said defuzzification step generates a real value of said at least one of said base current and said gate voltage.

51. A process according to claim 50, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

52. A process according to claim 51, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

53. A process according to claim 52, wherein said calculation of said weight functions occurs on said antecedents.

54. A process according to claim 51, wherein said calculation of said weight functions occurs on said antecedents.

55. A process according to claim 50, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

56. A process according to claim 55, wherein said calculation of said weight functions occurs on antecedents.

57. A process according to claim 50, wherein said calculation of said weight functions occurs on antecedents.

58. A process according to claim 1, wherein said process employs as said rules rules of an IF-THEN type, which rules define an antecedent and a consequent.

59. A process according to claim 58, wherein said defuzzification step comprises the calculation of centroids of the membership functions of said consequents.

60. A process according to claim 59, wherein said calculation of said weight functions occurs on said antecedents.

61. A process according to claim 58, wherein said calculation of said weight functions occurs on said antecedents.

62. A process according to claim 1, wherein said defuzzification step comprises the calculation of centroids of the membership functions of consequents.

63. A process according to claim 62, wherein said calculation of said weight functions occurs on antecedents.

64. A process according to claim 1, wherein said calculation of said weight functions occurs on antecedents.

65. A fuzzy control device for switching a power supply which has at least one inductor and at least one switching device comprising:

means for measuring a value of a current in said inductor;
means for measuring a value of an input voltage of said switching power supply;
means for detecting an error generated between a reference voltage and an output voltage of said power supply;
fuzzy inference means for applying said measured values and fuzzy membership functions for said current value on said inductor, for said input voltage value, for said error, and for a value of a duty cycle of said power supply, and
to a plurality of fuzzy inference rules,
means for calculating corresponding weight functions of said membership functions; and
means for defuzzifying results obtained by said means for calculating and said means for applying, said means for defuzzifying being for producing a real value of said duty cycle for driving said switching device, and said means for defuzzifying being responsive to said means for calculating.

66. A device according to claim 65, wherein said switching device is a power transistor.

67. A device according to claim 66, further comprising means for measuring a value of a temperature of said power transistor; and wherein membership functions include a membership function for said temperature value.

68. A device according to claim 67, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and
said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

69. A device according to claim 68, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

70. A device according to claim 69, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

71. A device according to claim 70, wherein means for calculating performs said calculation of said weight functions on said antecedents.

72. A device according to claim 69, wherein means for calculating performs said calculation of said weight functions on said antecedents.

73. A device according to claim 68, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

74. A device according to claim 73, wherein means for calculating performs said calculation of said weight functions on antecedents.

75. A device according to claim 68, wherein means for calculating performs said calculation of said weight functions on antecedents.

76. A device according to claim 67, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

77. A device according to claim 76, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

78. A device according to claim 77, wherein means for calculating performs said calculation of said weight functions on said antecedents.

79. A device according to claim 76, wherein means for calculating performs said calculation of said weight functions on said antecedents.

80. A device according to claim 67, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

81. A device according to claim 80, wherein means for calculating performs said calculation of said weight functions on antecedents.

82. A device according to claim 67, wherein means for calculating performs said calculation of said weight functions on antecedents.

83. A device according to claim 66, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and
said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

84. A device according to claim 83, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

85. A device according to claim 84, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

86. A device according to claim 85, wherein means for calculating performs said calculation of said weight functions on said antecedents.

87. A device according to claim 84, wherein means for calculating performs said calculation of said weight functions on said antecedents.

88. A device according to claim 83, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

89. A device according to claim 88, wherein means for calculating performs said calculation of said weight functions on antecedents.

90. A device according to claim 83, wherein means for calculating performs said calculation of said weight functions on antecedents.

91. A device according to claim 66, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

92. A device according to claim 91, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

93. A device according to claim 92, wherein means for calculating performs said calculation of said weight functions on said antecedents.

94. A device according to claim 91, wherein means for calculating performs said calculation of said weight functions on said antecedents.

95. A device according to claim 66, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

96. A device according to claim 95, wherein means for calculating performs said calculation of said weight functions on antecedents.

97. A device according to claim 66, wherein means for calculating performs said calculation of said weight functions on antecedents.

98. A device according to claim 65, further comprising means for measuring a value of a temperature of said power transistor; and wherein membership functions include a membership function for said temperature value.

99. A device according to claim 89, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said power transistor; and
said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

100. A device according to claim 99, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

101. A device according to claim 100, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

102. A device according to claim 101, wherein means for calculating performs said calculation of said weight functions on said antecedents.

103. A device according to claim 100, wherein means for calculating performs said calculation of said weight functions on said antecedents.

104. A device according to claim 99, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

105. A device according to claim 104, wherein means for calculating performs said calculation of said weight functions on antecedents.

106. A device according to claim 99, wherein means for calculating performs said calculation of said weight functions on antecedents.

107. A device according to claim 98, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

108. A device according to claim 107, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

109. A device according to claim 108, wherein means for calculating performs said calculation of said weight functions on said antecedents.

110. A device according to claim 107, wherein means for calculating performs said calculation of said weight functions on said antecedents.

111. A device according to claim 98, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

112. A device according to claim 111, wherein means for calculating performs said calculation of said weight functions on antecedents.

113. A device according to claim 98, wherein means for calculating performs said calculation of said weight functions on antecedents.

114. A device according to claim 65, wherein:

said membership functions include a membership function for the value of at least one of a base current and a gate voltage of said switching device; and
said defuzzification means are for generating a real value of said at least one of said base current and said gate voltage.

115. A device according to claim 114, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

116. A device according to claim 115, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

117. A device according to claim 116, wherein means for calculating performs said calculation of said weight functions on said antecedents.

118. A device according to claim 115, wherein means for calculating performs said calculation of said weight functions on said antecedents.

119. A device according to claim 114, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

120. A device according to claim 119, wherein means for calculating performs said calculation of said weight functions on antecedents.

121. A device according to claim 114, wherein means for calculating performs said calculation of said weight functions on antecedents.

122. A device according to claim 65, wherein said fuzzy inference means are for applying said measured values and said membership functions to ones of said rules that are of an IF-THEN type and that define an antecedent and a consequent.

123. A device according to claim 122, wherein said defuzzification means are for calculating centroids of the membership functions of said consequents.

124. A device according to claim 123, wherein means for calculating performs said calculation of said weight functions on said antecedents.

125. A device according to claim 122, wherein means for calculating performs said calculation of said weight functions on said antecedents.

126. A device according to claim 65, wherein said defuzzification means are for calculating centroids of the membership functions of consequents.

127. A device according to claim 126, wherein means for calculating performs said calculation of said weight functions on antecedents.

128. A device according to claim 65, wherein means for calculating performs said calculation of said weight functions on antecedents.

129. A process according to claim 1 wherein the process controls a DC/DC converter as said power supply.

130. A process according to claim 129 wherein the process controls a flyback DC/DC converter as said power supply.

131. A process according to claim 4 wherein the process controls a DC/DC converter as said power supply.

132. A process according to claim 131 wherein the process controls a flyback DC/DC converter as said power supply.

133. A fuzzy control device according to claim 65 wherein said power supply is a DC/DC converter.

134. A fuzzy control device according to claim 133 wherein the DC/DC converter is a flyback converter.

135. A fuzzy control device according to claim 68 wherein said power supply is a DC/DC converter.

136. A fuzzy control device according to claim 135 wherein the DC/DC converter is a flyback converter.

Referenced Cited
U.S. Patent Documents
4940929 July 10, 1990 Williams
5297015 March 22, 1994 Miyazaki et al.
5349523 September 20, 1994 Inou et al.
5493485 February 20, 1996 Okado
Other references
  • APEC '93, Mar. 7, 1993, San Diego, CA, USA pp. 22-28, Lin, "Analysis of Fuzzy Control Method Applied to DC-DC Converter Control". Intelec '91, Nov. 5, 1991, Kyoto, Japan, pp. 261-267, Ueno, Oota & Sasaki, "Regulation of Cuk Converters Using Fuzzy Controllers".
Patent History
Patent number: 5696439
Type: Grant
Filed: Jun 30, 1995
Date of Patent: Dec 9, 1997
Assignee: Consorzio per la Ricerca sulla Microelettronica nel Mezzogiorno (Catania)
Inventors: Matteo Lo Presti (Misterbianco), Giuseppe D'Angelo (Misterbianco), Antonino Cucuccio (Catania)
Primary Examiner: Peter S. Wong
Assistant Examiner: Shawn Riley
Attorney: Wolf, Greenfield & Sacks, P.C.
Application Number: 8/497,726